Giardiasis

Giardiasis is a gastrointestinal infection that causes diarrhea. It is caused by a parasite called Giardia lamblia, or Giardia intestinalis.

What is going on in the body?

Giardiasis occurs all over the world. The infection is found in the stool of an infected person or animal. It can be excreted into the environment. The parasite has a protective shell that allows it to live for long periods of time in the environment. It can be found in drinking water and in recreational bodies of water, such as lakes. Giardiasis is the most common waterborne disease in the United States.

What are the causes and risks of the infection?

Giardiasis is spread by contact with the parasite that causes the infection. The parasite can be found in food, water, soil, and other surfaces contaminated by stool from an infected person. A person can be infected in several ways:

What are the signs and symptoms of the infection?

Most people who have giardiasis do not have symptoms. When symptoms do occur, they usually include:

In more severe cases, people can lose weight and children may stop growing. People with weakened defense systems or people with cystic fibrosis can develop more serious problems from the infection.

How is the infection diagnosed?

Diagnosis of giardiasis begins with a medical history and physical exam. A specimen of the person's stool may be checked in the lab for signs of the parasite.

What can be done to prevent the infection?

Many cases of giardiasis can be prevented by taking the following steps:

What are the long-term effects of the infection?

In severe cases, there may be weight loss or stunted growth in children.

What are the risks to others?

Anyone who has the organism in the feces can spread it to others, especially if they have poor hygiene practices. Infected people should use good handwashing techniques. They should not swim in pools or other bodies of water until the infection is gone.

What are the treatments for the infection?

Metronidazole is the medicine of choice for most people with giardiasis. Other treatments include furazolidone for children and paromomycin for pregnant women.

What are the side effects of the treatments?

People taking metronidazole should avoid alcohol. Some side effects are as follows:

What happens after treatment for the infection?

Giardiasis usually responds readily to the medicine and recovery is complete.

How is the infection monitored?

The provider may request a stool sample to be sure the parasite has been eliminated. Any new or worsening symptoms should be reported to the healthcare provider.

Author:Danielle Zerr, MD
Date Written:
Editor:Ballenberg, Sally, BS
Edit Date:09/30/01
Reviewer:Eileen McLaughlin, RN, BSN
Date Reviewed:09/10/01